Larian Studios

In the Wyrm Rock Fortress boss fight, I was annihilated by all the turrets and had to restore. The second time, I shot out all the turrets before the fight, and then the boss was easy. I don’t enjoy this game design. It felt like I was set up to fail the first time, and the game positioned me so that I would have to load to succeed. I would prefer a middle road where the turrets aren’t so brutal but can’t be killed before the fight.

Huh. Attempting to destroy a turret before the fight has always initiated the fight for me, even sneaking, but... I always thought the point of that fight was that I had to take out the grenade launchers and flamecasters, at least the ones near my party's initial position, before I dealt with the Banites. Unless you're getting wiped by the turrets exploding when you defeat them, that's more of a failure of threat assessment than it is a problem with the encounter design itself. And if you can successfully sneak and take out the turrets beforehand, then that's the game rewarding you for playing things sideways. Not really any different than barrelmancy.

I do think the boss himself is very underwhelming, but I suspect it's kind of the point that that character is protected by all his gizmos and power structures, and isn't very formidable when stripped of them.

It's possible to take out the turrets pretty easily with eldritch blasts from outside; you won't get them all but once inside you just have to avoid the firing arcs of any you left (or polish off the last of them). I agree with the OP that it's one of the weaker boss fights as it can be either way too difficult, or way too easy. Plus you can farm the grenade launchers for lobbing grenades at Gortash to make the fight even easier.

Huh. I've always brought Wyll to that fight ever since the first time I did it (and discovered how good Eldritch Blast is for taking out the turrets), and trying to snipe the turrets from outside of the room has always automatically aggroed the people inside for me, even if I do it while sneaking with invisibility. Evidently I need to git gud.
 
Tactician/honor mode at least fixes the grenade launchers assisting you by making the grenades impossible to pick up. On balanced/easy, I think making them explode in your inventory unless they're thrown that turn, instead of letting one character pick all of them up and use or save them at their leisure, would be enough of a nerf to force you to still have to think about how you're handling them.